From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3BBEA134A8; Thu, 14 Aug 2025 08:22:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755159772; cv=none; b=XVs/UJBJFxoHN2Ma6O4w75c2+V9jVpqvL3sq9OFkE0ZNt9V4fEKdibSdKnlCvKRzxRxR0PcAkO3TMfyk3xKWPHQ/0yte15nCCDKhJLJtcb5UqKW+ftdL0G1zH5Fn1ETxtsopkz0SnI8TQGQ4X+PsaMFzPI0aMyVcALG0ts0Q5+g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755159772; c=relaxed/simple; bh=jDpZP4/rNLVTvGT095fabT5/KURL5z51C/V+cp3uqr8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oX7lyREcK0vJD7h2JOx/k9cS/XHeLuoTm58XQsd89KLosuiu9KeDWFJPS5UG9wNR3TDxLu7l+EFHTkIhA5fPwiLjPeV8q1m5BU9hP9q0O2DwCRCVDSeoivM55oCxj2Q2WWD+zGwQXlyLqWtSfJKbyl+KhH3yPsEvUgM1FtdLqXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kJfRKMlj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kJfRKMlj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 400BAC4CEEF; Thu, 14 Aug 2025 08:22:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755159771; bh=jDpZP4/rNLVTvGT095fabT5/KURL5z51C/V+cp3uqr8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=kJfRKMljuO7qOl8Oz2kROIAC87g7Piuq15ez4yMPKEk7+Tjn2V8PphhWdKsvjpaKf IVszWIGYr0po86vThtEbfjgTM3sANaeTnkBWfARRH1O5igYX8HkHpoKzdgcVTIUIso iqEd0pBlszTAyqWhUvcnk8UMnnx7YhesQfV0TCP9o/qiimJJvD4WSY4PYWmnFe6upV gJfIV7oVe6qBiJ6l5/55c3VUENPG2sOg/l8o8Yu6CCyFm1VRYtYIbLrg0W+vSq6U4K 4ydjPJLII5Ef0z5CjVXeabt49t8F4l13iv5OSevvPfZQ7Gty+MwhXvbUAGlagQr61I pgw9bvbgEn49g== Message-ID: <17955c87-1a82-4eae-94ee-3ac1447d4e71@kernel.org> Date: Thu, 14 Aug 2025 10:22:48 +0200 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6.16 199/627] sched/deadline: Less agressive dl_server handling To: Greg Kroah-Hartman , stable@vger.kernel.org Cc: patches@lists.linux.dev, Chris Mason , "Peter Zijlstra (Intel)" , Juri Lelli , Sasha Levin References: <20250812173419.303046420@linuxfoundation.org> <20250812173426.853672780@linuxfoundation.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 12. 08. 25, 19:28, Greg Kroah-Hartman wrote: > 6.16-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Peter Zijlstra > > [ Upstream commit cccb45d7c4295bbfeba616582d0249f2d21e6df5 ] > > Chris reported that commit 5f6bd380c7bd ("sched/rt: Remove default > bandwidth control") caused a significant dip in his favourite > benchmark of the day. Simply disabling dl_server cured things. > > His workload hammers the 0->1, 1->0 transitions, and the > dl_server_{start,stop}() overhead kills it -- fairly obviously a bad > idea in hind sight and all that. > > Change things around to only disable the dl_server when there has not > been a fair task around for a whole period. Since the default period > is 1 second, this ensures the benchmark never trips this, overhead > gone. This causes: sched: DL replenish lagged too much Maybe some prereq missing? > Fixes: 557a6bfc662c ("sched/fair: Add trivial fair server") > Reported-by: Chris Mason > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Juri Lelli > Acked-by: Juri Lelli > Link: https://lkml.kernel.org/r/20250702121158.465086194@infradead.org > Signed-off-by: Sasha Levin thanks, -- js suse labs